Many features observed by the Geomorphologist raise an interesting question, namely: do all the observations belong to one or more morphological populations? Detailed field measurements of form may help solve this type problem, but in doubt-ful cases one may have to resort to some statistical device which allows a certain probability to be attached to an individual that will help decide to which of two possible populations it belongs.

In this paper we shall describe an example of a problem raised during the map-ping of terracette forms near Salford where there was good documentary evidence that the forms belonged to two populations, natural and man made. Visually, the two populations of terracettes appeared similar and it seemed reasonable to suppose that only careful measurement of the actual morphology might distinguish them.

In dubious cases assignment to one population or the other can be made via logistic regression, which because of its properties is advantageous to other met-hods which might be used to discriminate between the two genetic types of terracette. Hitherto this type of statistic has been little used in Geography, but as we shall indicate it has considerable advantages over other commonly used methods such as ordinary least squares regression and discriminant analysis.

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Peter Vincent, University of Lancaster, Lancaster, United KingdomJean Haworth, University of Salford, Salford, United KingdomJoan Victoria Clarke, University of Salford, Salford, United Kingdom

The present article discusses only one section of the problems connected with this issue, i.e. changes in the structure of water circulation under the influence of man's activity. Nothing is said of the equally important issues of changes in water quality and water relationships, the latter being closely connected with the structure of circulation and examinable only with definite examples.

Geographers have increasingly been trying to measure and work with variables that deal with cognitive information (Downs and Stea, 1973 and Gould and White, 1974). The usual purpose for gathering cognitive information is to use it as an in-dépendant variable to explain the distribution of some pattern produced by the decisions of individuals who supposedly used the information as the basis of their decisions. It is clearly an attempt to relax the economic man assumption frequently used in deterministic models which assume that man as a decision-maker has perfect information and also has perfect ability to use the information (Wolpert, 1966). Although a number of studies have used techniques borrowed from psychology to measure the specific beliefs and attitudes subjects have concerning individual geo-graphic units (Downs, 1970; Burnett, 1973; Demko, 1974; Lowenthal and Riel, 1972; and Lloyd, 1975), few attempts have been made to measure the total amount of infor-mation individuals or groups of individuals have acquired for specific geographic units. The total amount of information, although it is perhaps more difficult to accurately measure than specific beliefs and affects, would seem a logical starting point as we try to build knowledge of the cognitive environment.

Peter Vincent, University of Lancaster, Lancaster, United KingdomRobert Collins, The University of Lancaster, Lancaster, United KingdomJohn Griffiths, The University of Lancaster, Lancaster, United KingdomJean Haworth, University of Salford, Salford, United Kingdom